Impact of duration of bevacizumab (Bev) treatment in the prognosis of adults with recurrent malignant gliomas.

Abstract

2064 Background: Bev is the standard treatment for patients with recurrent glioblastoma (GB) but is also used in treating recurrent anaplastic gliomas (AG). Differences in outcome between these groups and optimal duration of treatment with Bev in pts with recurrent malignant gliomas are not well defined. We examined the relationship between the duration of Bev treatment and the outcome in pts with GB and AG. Methods: In this retrospective chart and data review derived from our longitudinal database, we identified pts with recurrent AG and GB who were treated with Bev alone or Bev-containing regimens between 2005 and 2009; the data was analyzed to determine the overall survival (OS) and the progression free survival (PFS). Results: A total of 261 patients with recurrent malignant gliomas (196 with GB and 65 with AG) were identified. There was no significant difference between the median length of treatment between AG and GB (5.81±0.66 months vs. 6.77±0.52 months, p=0.32). PFS6 was 34.2% (95% CI, 27.8-41.3) for patients with GB and 44.2% (95% CI, 32.5-56.7) for patients with AG. Patients with GB who were treated ≥6 months had a significantly higher OS (29.13 months vs. 20.16 months, p= 0.001) compared to those treated <6 months, and a significantly higher PFS compared to those treated <6months (11.33 months vs. 3.7 months, p=0.0001). For patients with AG, although treatment ≥6 months had a significantly higher PFS (13.93 months vs. 3.53 months, p<0.0001), OS was not significantly different (months 38.6 vs. 52.5 months, p=0.6) compared with those treated <6 months. Conclusions: Length of treatment ≥6 mo with Bev or Bev-containing regimen was associated with improved PFS in both AG and GB but only the GB subgroup showed improved OS. These results suggest equivocal survival benefit in patients with AG with longer duration of bevacizumab treatment, which requires further study in prospective trials.